Dihaloamino-carboranes



United States Patent l 3,406,203 DIHALOAMINO-CARBORANES Scott I. Morrow, Morris Plains, Marvin M. Fein, Westfield, and Donald D. Perry, Morristown, N.J., assignors to Thiokol Chemical Corporation, Bristol, Pa., a corporation of Delaware No Drawing. Filed May 15, 1963, Ser. No. 281,382

28 Claims. (Cl. 260-583) This invention concerns new and useful halogenated boranes and to a method of preparing them.

More particularly, this invention relates to dihaloamino carboranes useful as explosives, propellant fuels, pyrotechnics and intermediates and adjuvants of explosives, propellants and pyrotechnics. These novel compositions wherein R is selected from the group consisting of hydrogen and alkyl groups having from 1-4 carbon atoms, n is a number ranging from O-6, X is a halogen selected from the group consisting of chlorine, bromine and fluorine, and R is selected from the group consisting of hydrogen and:

The alkyl groups of R can be straight chain or branched chains, joined or conjoined.

The term carborane(s) as used throughout this application refers to the structure:

Biu io To simplify the writing of structural formulas containing the carborane radical, the Greek letter 0 (theta) is used to represent the carborane radical.

Among the many structures included within the scope of this invention are the following;

3,406,203 Patented Oct. 15, 1968 stantially increased. For example, the addition of boron compounds such as the dialkyl boranes and born hydrides, to hydrocarbon based jet and rocket fuels results in a substantial gain in fuel performance and a significant saving of fuel weight. Because of these advantages over hydrocarbon based fuels, much effort has been expended to develop stable, high energy boron fuels for use as propellants and explosives. For these reasons the development of stable, high energy boron based fuels are important to the explosive and propellant art.

Thus it is an object of this invention to prepare high energy boron based fuels useful as rocket propellants and explosives when formulated with oxidizers, modifiers and adjuvants.

It is a further object of this invention to formulate boron based pyrotechnic compositions exhibiting a high degree of luminescence during ignition.

It is another object of this invention to prepare novel carboranes which can be used to introduce the carborane moiety in organic compounds.

Yet another object of this invention is to prepare high energy boron based binder precursors and other intermediates.

Other objects will become more apparent from a further examination of this application.

These objects as well as many others are accomplished by the synthesis of the novel carboranes of this invention described supra.

In its composition aspects, the compounds of this invention are advantageous in several respects. For example, the compositions of this invention have certain characteristics which make them superior to many commercially available hydrocarbon based fuels currently utilized as explosives or propellants. These are good stability, non-hydroscopicity, relatively low sensitivity toward impact and desirable combustion products. For example the novel dihaloamino carboranes of this invention are relatively unaffected by exposure to heat, light and oxidation and are stable to decomposition for extended periods of time. In addition, these compositions are only a fraction as sensitive to impact sensitivity as nitroglycerine and yet function as comparable explosives when formulated with oxidizing agents used in the explosives and propellants art. A major reason that these novel boron based compositions are superior to hydrocarbon based fuels as explosives and propellants is because of their favorable combustion products. By this it is meant that the major products of the combustion of dihaloamino carboranes have exceedingly high negative heats of formation compared to the combustion products of hydrocarbon based fuels and explosives and thus release much more thermal energy during combustion than do the comparable hydrocarbon products. This can be seen by the table below which shows the much higher negative heats of formation of the difluoroamino-carboranes combustion products (OBF and H30 compared to the combustion products of a typical hydrocarbon based propellant fuel such as kerosene. In the latter case the combustion products are primarily CO CO and H 0.

TABLE Combustion products: Heats of formation Kcal./mole OBF 123 HBO 134 H O 58 CO 94 CO 26 An additional advantage of these boron basic compositions when used as explosives, propellants or pyrotechnic fuels or components is their compatibility with a great number of components common to propellants, explosives and pyrotechnics. These components herein generally referred to as explosive adjuvants include modifying and conditioning agents used to impart, change, or alter the physical and/ or chemical characteristics of the explosive mixtures so as to effect the explosive force.

These explosive adjuvants include among others: absorbing agents, extending agents, plasticizing agents, emulsifying agents, stabilizing agents, coloring agents, solubilizing agents, ballistic agents, inhibiting agents, cooling agents, binding agents and the like. These adjuvants are usually present in fractional percentages but can be present in sufi'icient quantities in certain instances to make up a substantial portion of the explosive composition. One or more of these adjuvants can be combined with the novel carborane fuels of this invention and one or more oxidants to formulate the explosive, propellant or pyrotechnic compositions useful for a variety of purposes. Among the more satisfactory oxidants which can be used are: the inorganic or organic perchlorates such as and NO ClO and the inorganic and organic nitrates such as NH NO and the aromatic and aliphatic nitro compounds such as TNT and tetranitromethane, as well as organo-difluoramines such as tris (difiuoramino) propane and the like. In some instances the combination of adjuvants, fuels and oxidizers produce compositions having enhanced explosive or propulsive properties for reasons presently unclear.

An additional and advantageous attribute of the novel compositions of this invention is the high degree of luminescence exhibited during ignition. This characteristic along with the compounds, stability and compatibility with adjuvants and oxidants, make the novel dihaloaminocarboranes useful as fuels or components of pyrotechnic compositions and formulations. Common uses of these pyrotechnic compositions are in signal and illuminating flare devices. Further uses wherein the composition of this invention are advantageous is where they are utilized as intermediates for preparing explosives, explosive binders, explosive adjuvants and pyrotechnic compositions as well as organic intermediates generally. The reactive nitrogen dihalide groups can be further reacted with other reagents containing reactive groups to form monomeric or polymeric products of altered structure and characteristics.

In practice, dihaloamino-carboranes of this invention are prepared by the reaction of a dinitrogen tetrahalide with an ll-alkenyl carborane. The general reaction appears below:

Wherein n is a number ranging from 6, R is selected from the group consisting of hydrogen and alkyl groups having from l-6 carbon atoms, and X is a halogen, R has the meaning previously ascribed and R is selected from the group consisting of H and R1 ]=CHz While the salient advantages of this invention reside in its composition aspect, the process does offer advantages other than the novelty of the dihaloamino-carborane products. Among these advantages are low cost and availability of the reactants, flexibility of reaction conditions, and substantial freedom from competing and untoward side reactions.

For example, both the reactants of this invention process can be prepared by published synthetic procedures or by modifications of these procedures. The dinitrogen tetra fluorides can be prepared by the reaction of fluorine and ammonia as described by S. Morrow et al., J. Am. Chem. Soc.; 82, 5301 (1960) while the ll-alkenyl carboranes are prepared by the reaction of a suitable acetylenic compound with a substituted decaborane of the type B H (ligand) where the ligand may be a sulfide or nitrile. These preparations are described in copending application Ser. No. 113,547 filed May 29, 1961 in the United States Patent Offi-ce.

In practice a mixture of the two reactants are heated together in a sealed reaction chamber, with or without a suitable diluent or solvent, to form the products of this invention. The product is isolated and purified by extracting with an alkane and decolorized using activated carbon. A suitable diluent or solvent is one in which either or both of the reactants are soluble in and which is inert to the action of the reactants. Examples of suitable solvents include the following: n-pentane, n-hexane, isomeric mixtures of the pentanes or hexanes, cyclohexane and the like. The order of addition of the reactants is immaterial. Similarly the ratio of the reactants to each other is not critical as long as at least a stoichiometric excess of the dinitrogen tetrahalide react is present. In practice any quantity of the dinitrogen tetrahalide from a stoichiometric excess to 4 moles or more is satisfactory to prepare the products of this invention. i

The operable process temperatures required to produce the desired products range from between 75250 C. However, below C. the reaction time becomes unduly extended and for this reason temperatures below 125 C. are inconvenient. At temperatures above 200 C. the course of the reaction time is shortened compared to lower temperatures, but the reaction becomes too violent and side reactions become an important factor. For this reason reaction temperatures between 125 C. to 200 C. are favored with the narrower range of 160 C. being the preferred operating temperature range.

The process of the invention can be operated at pressures ranging from Subatmospheric to super-atmospheric. Subatmospheric pressures slow down the reaction rate appreciably and for this reason offer little advantage. Superatmospheric pressures do offer the advantage of reducing the reaction temperature but require the use of costly process equipment and increase safety hazards. For these reasons it is preferred to operate the process of this invention at substantially atmospheric pressures.

Because of the experimental variables involved, such as the reactivity of the different reactants, the operating temperatures and pressures and the like, the reaction time cannot be stated with precision. However, the extremes of reaction time fall within 224 hours, with 10-16 hours being the more usual range under preferred conditions of temperature and pressure.

To more clearly set forth the inventive compositions and process the following examples are submitted.

Example 1.-Preparation of 1,2-bis(difiuoroamino)- 4(11-carboranyl) butane One mole of l1-(3-butenyl) carborane and three moles of dinitrogen tetrafiuoride are added to a suitable reaction chamber provided with agitation and heating means and a condenser. The agitated react-ants are heated to and kept at 145160 C. during the heating step.

During the course of the heating step a quantity of a gaseous by-product is evolved, collected and discarded. The product of the reaction (a brown, viscous oil) is collected and extracted with pentane and decolorized with activated carbon. Infra-red analysis and wet analysis of the product confirmed the identity of the product as 1-2- bis(difiuoroamino) -4- 1 l-carbonyl) butane.

The n-pentane insoluble fraction from above was treated with benzene and the still insoluble fraction solubilized by the addition of acetone. Both fractions when purified gave related but dissimilar spectra upon infra-re analysis.

Example 2.-Preparation of 1,2-bis (difluoroamino)-2- (ll-carborane) propane One mole of 1l-(isopropenyl)-carborane and 2 moles of dinitrogen tetrafluoride are added to a suitable chamber provided with agitation and heating means and a condenser. The agitated mixture of reactants is heated at 146-160" C. for 14 hours. During the course of the reaction a gaseous by-product is evolved, collected and discarded during the work-up of the products. The product of the reaction is contained in a brown viscous material which is purified by dissolution into n-pentane and decolorized by treating with activated carbon. Elemental analysis and infra-red analysis indicated close agreement with the structure of 1,2-bis (difiuoroamino)-2(l1-carboranyl) propane.

The n-pentane insolubleby-product is treated first with benzene and the insoluble fraction with acetone. The acetone and benzene soluble materials had related but not identical structures by infra-red analysis.

Examples 3-6.Preparation' of representative products of this invention Using the procedure and techniques described in Examples 1 and 2, the following products are prepared using the reactants given below:

Ex. N o. Reactant 1 Reactant 2 Product 3 NQFQ ll-(ethenyl) carbornne... 1,2-bis(difiuoroamino)2-(11- carboranyl) ethane.

4 NzF; 11-(5hexenyl)carborane l,2-bis(difiuoroaminoHi-(llcarboranyl) hexane.

11,12 bis 1,2-bis(difluoroamin0)-2 (11- cal-boranyl) propane.

11,12 bis 1,2-bis(difluoroamino)-4 (ll-carboranyl) butane.

5 N2F4 11,12-bis(isopropenyl) carborane.

6 N F; 11,12 bis(butenyl) carborane.

In all instances the structure of the products is confirmed by infra-red analysis.

Example 7.Testing of representative products of this invention as explosives (A) DETONATION Example 8.-Testing of representative compounds of this invention as trip flares Using the products obtained in Examples 1 and 2, the following 2 different pyrotechnic compositions are made A. COMPOSITION 1 Component: 7 Parts by weight Aluminum 21.5 1,2bis(difluoroamino)-2(1l-carboranyl) propane 69.5 Sodium oxalate 5.0 Sulfur 4.0

6 B. COMPOSITION 2 Magnesium 30.4 Sodium nitrate 11.0

Gilsonite 5.0 Castor oil 1.1 Linseed oil 1.1

1,2-bis(difiuoroamino) -4( 1 l-carbooranyl) butane 19.3

Both compositions when tested gave green flares of extreme luminescence.

We claim:

1. Dihaloamino carboranes of the formula:

wherein R is selected from the group consisting of hydrogen and alkyl groups having from 14 carbon atoms, 11 is a number ranging from 0-6, X is a halogen selected from the group consisting of chlorine, bromine, and fluorine, and R is selected from the group selected from hydrogen and:

wherein X has the same meaning given above.

2. The dihaloamine carboranes of claim 1 wherein X is fluorine.

3. The dihaloamine carboranes of claim 1 wherein X is chlorine.

4. The dihaloamine carboranes of claim 1 wherein X is bromine.

. 0 (CH CHNF CH NF h.

18. The process of preparing dihaloamine carboranes comprising the step of contacting a dinitrogen tetrahalide of the formula: N X with ll-alkenyl carboranes of the formula:

wherein R is selected from the group consisting of hydrogen and alkyl groups having from 14 carbon atoms, 11 is a number ranging between 0-6, X is a halogen selected from the group consisting of chlorine, bromine and fluorine, and R is selected from the group consisting of hydrogen and:

until a dihaloamino-carborane of the formula:

where X, n, R have the meaning previously ascribed to them, R is chosen from the group consisting of H and is formed and isolating said dihaloamino carborane product. a

19. The process of claim 18 wherein the halogen is fluorine.

20. The process of claim 18 wherein the halogen is chlorine.

21. The process of claim 18 wherein the halogen is bromine.

22. The process of claim 18'wherein the halogen is fluorine and the ll-alkenyl reactant is: HCH=CH '23. The process of claim 18 wherein the halogen is fluorine and' the ll-alkenyl reactant is:

24. The process ofgc laim' l8 wherein the halogen fluorine and the ll-alkenyl reactant is:

" H0-"CH C( CH )"=CH -25. The process of claim 18.Wherein the vhalogen is fluorine and the ll-alkenyl reactant is 0(CH CH '26. The process of claim 18 wherein the halogen fluorine and the ll-alkenyl reactant is: a a

H 3) 2)2 ,27. The process of claim 18 wherein, the .halogen is fluorine .and the ll-alkenyl reactant is: :7 t

I v 2C( 3) 2)2 28. The process of claim 18 wherein the halogen fluorine andthe ll -alkenyl reactant is;

-- References Cited UNITED STATES PATENTS 3,152,190 10/1964 Schwartzet a1 149-22 X LELAND'B. SEBASTIAN, Primary Examiner. 

1. DIHALOAMINO CARBORANES OF THE FORMULA:
 18. THE PROCESS OF PREPARING DIHALOAMINO CARBORANES COMPRISING THE STEP OF CONTACTING A DINITROGEN TETRAHALIDE OF THE FORMULA: N2X4, WITH 11-ALKENYL CARBORANES OF THE FORMULA: 